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CHAPTERTWO Proposed Action and Alternatives <br />• The elevations of section corner markers within the well field would be measured relative to <br />benchmazk elevations once every 6 months during commercial operations. <br />This monitoring would mainly track subsidence at the surface, which would be a result of <br />' subsurface subsidence. American Soda has committed to attempt to use Time Domain <br />Reflectometry (TDR), an electrical measurement technique used to determine spatial location <br />and nature of various objects, to monitor subsurface subsidence. In consultation with BLM, <br />' American Soda would evaluate the feasibility of TDR during the experimental test mine <br />operations. If successful, the use of this technology would be added to the subsidence <br />monitoring program. If TDR does not prove to be an adequate means of monitoring subsidence, <br />the BLM will require that one monitoring well be established in each mine panel. A suite of <br />downhole geophysical logs would be run in this hole on an annual basis, including baseline <br />before mining commences, to monitor subsurface subsidence. <br />2.2.5.3 Groundwater Quality and Water Level Monitoring <br />' A series of monitoring wells would be located in the well field to monitor groundwater quality <br />and water levels. Three experimental test phase monitoring wells aze currently monitored for test <br />' phase operations. These and seven other existing monitoring wells would be used to monitor the <br />initial 0-5 yeaz mining panel. The locations of the monitoring wells relative to the 0-5-yeaz <br />mining panel aze indicated in Figure 2-10. Figure 2-11 shows a typical monitoring well section. <br />' The results of groundwater monitoring for the first 5 yeazs of mining would be used to develop <br />an appropriate monitoring program for subsequent 5-yeaz mining panels. Additional monitoring <br />wells would be established at appropriate downgradient locations in conjunction with <br />development of each subsequent 5-yeaz mining panel. It is anticipated that each panel would <br />have at least one upgradient and one downgradient monitoring well. These monitoring wells <br />would likely monitor the Dissolution Surface because groundwater at this location is closest to <br />the solution mining interval (approximately 150 feet). Specific well locations and tazget <br />monitoring horizons for each well would be determined in consultation with the BLM, CDMG, <br />' and EPA. The monitoring wells would be in place and collecting baseline data 6 months prior to <br />commencing mining activities in a panel. <br />Monitoring of water quality and water level in bedrock aquifer wells at the Piceance Site would <br />occur on a monthly basis. Monthly monitoring well samples would be analyzed for a minimum <br />of the following constituents: <br />• pH <br />• conductivity <br />' total dissolved solids <br />• alkalinity <br />• sodium bicazbonate <br />• sodium cazbonate <br />• fluoride <br />2-21 <br />